Sap flow estimated by compensation heat-pulse velocity technique in olive trees under two irrigation regimes in southern Italy

The optimal water supply to olive orchards needs the knowledge of crop water consumption. Tree transpiration can be estimated by measuring sap flow with the compensation heat-pulse velocity (CHPV) technique that in Olea europaea (L.) has been used in Spain with promising results. In 1999, in a 7-year-old olive orchard in southern Italy, CHPV was monitored both in three trees of the rain-fed (T0) and in three trees of the irrigation treatment (T100) that received, respectively, 0 and 100% of crop evapotranspiration. The CHPV-estimated sap flow from mid July to end November resulted in an average double value for the T100 (1.47 m(3) per plant) compared with the T0, while both showed good correlation with evapotranspiration. Results indicated that CHPV technique can be useful tool in eco-physiological studies but the heterogeneity of the conductive area should be accounted for to obtain a good estimation of the actual tree transpiration.